For example, in Japanese Patent Application Laid-Open Publication (Translation of PCT Application) No. 2007-536657 (Patent Document 1), in a system formed of a plurality of servers and a management server, power consumption of the system is reduced by consolidation by means for virtualization. When the management server detects a resource utilization or power consumption representing workloads of the servers via a monitoring agent and a detected value of a certain server is determined as being smaller than a threshold value, a virtual machine in that server is caused to dynamically migrate to another server, and power supply of the original server is cut off. For threshold determination, detected instantaneous values or average values are used. As resource utilization, a utilization of a processor, a memory, or the like is used.
In Japanese Patent Application Laid-Open Publication (Translation of PCT Application) No. 2005-531047 (Patent Document 2), in a method of managing power consumption of a server pool formed of a plurality of servers, the number of servers satisfying a total demand of an immediate workload is determined, and power consumption is managed by energizing or cutting-off the servers. To a current workload, a raised value (lower limit) or an excessive value (upper limit) is added, and when the workload that the currently operating server can handle is smaller than the lower-limit value, an operating server is added. When the workload exceeds the upper-limit value, the number of the servers is decreased. In order to follow a total demand of workloads by increasing or decreasing the number of servers, it is assumed that each workload has a sufficiently short life in terms of time, such as electronic commerce and Web applications.
In Patent Document 2, for a metric of workloads, processor utilization, memory utilization, network bandwidth utilization, and disk bandwidth utilization are used. As a raised value and an excessive value, a minimum deviation and a maximum deviation, respectively, of a workload observed within a history time frame are used, and also, by comparing and searching an actual workload demand and power consumption with respect to a history size of the workloads and settings of the raised value and the excessive value, finding an optimum setting is performed. For a repetitive and cyclic workload spike in days, weeks, or others, a flag is set at an operation schedule of a server pool for handling. Also, a server to be operated in accordance with a position of a cooling fan in a server chassis and a fault location is controlled.
In U.S. Patent Application Publication No. 2006/0259621 (Patent Document 3), in a method of allocating workloads to a plurality of servers in a data center, a profile of a workload requested is compared with a history profile, and the requested workload is allocated to a server according to a history in which the power of the server and an air conditioner is minimum. If no matching history is present, random allocation is made. The history profile includes positions and classes of the servers, types of the workloads and their utilization, injection and emission air temperatures, and power of the server and air conditioner. The power of the server and air conditioner is obtained from injection and emission air temperatures of the server, a specific heat, and the volume of air, or is measured by a power meter. As a history profile, an instantaneous value is regularly collected at short intervals (one to ten minutes) or long intervals (one to six months), and additionally, in the case of irregular collection within one day, when an event such as new allocation of a workload or a change of server arrangement is taken as a trigger, an experiment may be performed in which the allocation, type, utilization, and others of the workloads are changed in a wide range.
In Japanese Patent Application Laid-Open Publication No. 2005-312142 (Patent Document 4), in a system of managing power consumption of a building, power consumption is measured by sectioning the building and devices that are present therein. When power in a certain section exceeds a threshold value, a warning is issued to manage the power of the entire building to support power saving. The building is sectioned in floors, and the devices are sectioned in types, such as an information device and an air conditioner. A threshold value for each section is set with the use of an average value of power consumption in consideration of a deviation value.    Patent Document 1: Japanese Patent Application Laid-Open Publication (Translation of PCT Application) No. 2007-536657    Patent Document 2: Japanese Patent Application Laid-Open Publication (Translation of PCT Application) No. 2005-531047    Patent Document 3: U.S. Patent Application Publication No. 2006/0259621    Patent Document 4: Japanese Patent Application Laid-Open Publication No. 2005-312142